Thread Clamp for a Rapier Head and Method for the Operation of the Same

ABSTRACT

A thread clamp for a rapier head ( 10 ) for the firm clamping of weft threads ( 2, 2′, 2″, 2′″ ) in a rapier weaving machine is presented. The thread clamp ( 1 ) has first and second holding members ( 3, 4 ) which can be pressed against one another in a clamping region ( 3   a,    4   a ) in order to hold the weft threads. Moreover, one or more deflection elements ( 7, 7′ ) are provided at the thread clamp in order to deflect the weft thread or threads ( 2, 2′, 2″, 2′″ ) and to increase the holding force, with at least one deflection element ( 7, 7′ ) being controllable.

BACKGROUND OF THE INVENTION

The invention relates to a thread clamp for a rapier head for the firm clamping of weft threads in a rapier weaving machine in accordance with the preamble of claim 1, to a rapier head having such a thread clamp and to a method for the operation of such a thread clamp as well as to a rapier weaving machine having such a thread clamp or with such a rapier head or equipped to carry out such a method.

In rapier weaving machines the weft thread is inserted into a shed by means of a bringer rapier secured to a rapier rod or to a flexible tape and is taken over and transported further by a taker rapier at a transfer point in the central part of the shed. The bringer rapier has the task of reliably taking up the presented weft thread, of inserting the same into the shed and precisely bringing it to the taker rapier. Each of the rapiers includes a rapier head with a thread clamp in order to firmly clamp the weft thread during the weft insertion. With automatically clamping thread clamps, i.e. passive thread clamps, the thread take-over takes place by pulling the weft thread into or pulling it out of preset clamping regions of the respective thread clamp. For the manufacture of fabrics having weft yarns of different thickness or different smoothness controlled thread clamps can be used in one or in both rapier heads, with the thread clamp of the bringer rapier being actively opened or relieved whereas that of the taker rapier is actively closed or loaded.

Customary thread clamps mainly include a lever as a holding member, which, together with a second holding member, forms a wedge-like clamping gap for the firm clamping of weft threads, with the clamping gap tapering towards the point of rotation of the lever. The clamping force is weakest at the inlet to the thread clamp and now increases towards the interior of the thread clamp. If coarse and fine weft yarns have been inserted one after the other then a situation arises, particularly with automatically clamping thread clamps, in which the coarse weft threads, which require a larger clamping force, are initially firmly clamped during the take-up at the entry to the thread clamp where the clamping force is low so that the coarse weft yarns are only weakly held, whereas the fine weft yarns, which require a smaller clamping force, are drawn further into the thread clamp where they are correspondingly strongly held. In both cases break-downs in operation can arise in that the coarse weft yarns are not held sufficiently firmly during the weft insertion whereas the fine weft threads are too strongly held during the transfer to the taker rapier and can tear.

A further problem arises when two weft threads of different thickness are to be inserted simultaneously. In most cases the thread presenter does not permit a controlled sequence of the weft threads. If, for example, during the take-up of the weft threads, first a thicker weft thread and then a thinner weft thread arises, so that the clamping gap, which is mainly made resilient, is dilated additionally by the thick weft thread and then the danger exists that the subsequently taken up thinner weft thread is no longer adequately held in the clamping gap and becomes lost.

BRIEF SUMMARY OF THE INVENTION

The object of the invention is to make available a thread clamp for a rapier head for the firm clamping of weft threads in a rapier weaving machine, a rapier head having such a thread clamp and a method for the operation of such a thread clamp, as well as a rapier weaving machine with such a thread clamp, or with such a rapier head or equipped to carry out a method of this kind, which permit different weft threads and in particular also a plurality of different weft threads to be inserted one after the other or simultaneously with the same thread clamp.

This object is satisfied in accordance with the invention by the thread clamp defined in claim 1, by the rapier head defined in claim 8, by the method defined in claim 9 and by the rapier weaving machine defined in claim 14.

The thread clamp in accordance with the invention for a rapier head for the firm clamping of weft threads in a rapier weaving machine includes first and second holding members which can be pressed towards one an-other in a clamping region in order to hold one or more weft threads. Moreover, one or more deflection elements are provided at the thread clamp in order to deflect the weft thread or threads and to increase the holding force, with at least one deflection element being controllable. For this purpose the at least one deflection element can, if required, be pro-vided with its own actuator in order to actuate the deflection element, in particular separately from the two holding members. The actuator of the at least one deflection element can be made, for example, as a magnetic or piezo-electric actuator. The at least one deflection element can advantageously be controlled when the weft thread or threads are clamped in the thread clamp.

In an advantageous variant the two holding members are made automatically clamping and/or designed as a passive clamping device. In a further advantageous variant, the at least one deflection element is formed as a lever arm or arranged on a lever arm.

In a further advantageous variant the at least one deflection element is arranged in the clamping region and in a further advantageous variant to the side of the clamping region. Naturally it is also possible to provide a plurality of controllable deflection elements, for example one in the clamping region and respectively at one side or at both sides of the clamping region.

In the method in accordance with the invention for the operation of a thread clamp for a rapier head of a rapier weaving machine having first and second holding members, the two holding members are pressed to-wards one another in a clamping region, one or more weft threads are held in the clamping region and one or more deflection elements are provided by means of which the weft thread or threads is/are deflected and the holding force of the thread clamp is increased. In addition, for the insertion of the weft thread or threads at least one deflection element is con-trolled. If required the at least one controlled deflection element can be controlled for each individual weft insertion.

In an advantageous embodiment of the method, during the take-up and/or the transfer of the weft thread or weft threads, the at least one controlled deflection element can be retracted and/or the weft thread or threads can be additionally held during the insertion by means of the at least one controlled deflection element in that it dips into the path of the thread.

In a further advantageous embodiment of the method the weft thread or threads are pulled into the clamping region for reception, are held in the clamping region by the holding members which are pressed towards one another and subsequently the at least one controlled deflection element is dipped into the path of the thread.

In a further advantageous embodiment of the method, for the transfer of the weft thread or threads to the taker rapier, the at least one controlled deflection element is withdrawn from the path of the thread and the weft thread or threads are subsequently drawn out of the clamping region arranged in the bringer rapier head.

Furthermore, the invention relates to a rapier head, in particular to a rapier head of a bringer or taker rapier having a thread clamp in accordance with one of the above-described variants and also to a rapier weaving ma-chine having a thread clamp in accordance with one of the above-described embodiments and/or with a rapier head in accordance with the above description and/or equipped to carry out the method in accordance with the above description.

The thread clamp, the rapier head and the method in accordance with the present invention and also the rapier weaving machine in accordance with the present invention have the advantage in comparison to the thread clamps from the prior art that the same thread clamp can be used for a large range of different weft threads such as for example weft threads with different fineness, different texture or of different materials. The same applies to the case in which a plurality of different weft threads are to be inserted simultaneously. On the one hand the weft thread or threads are not hindered or injured during the take-up by the controllable deflection element or elements, since these can be withdrawn from the path of the thread and, during the insertion, the weft thread or threads is or are additionally held by the deflection element or elements which have dipped into the path of the thread. If required the controlled deflection element or the controlled deflection elements can be withdrawn during the transfer of the weft thread or threads to the taker rapier, in order not to hinder the pull-ing out of the same or not to injure them. If an automatically clamping thread clamp with the controllable deflection element is used instead of a customary controlled thread clamp then the cost and complexity of the force and energy required for the actuation of the deflection element is smaller since no clamping force has to be supplied or overcome during the actuation.

The above description of embodiments merely serves as an example. Further advantageous embodiments can be seen from the dependent claims and the drawing. Moreover, in the context of the present invention, individual features from the described or shown embodiments and variants can be combined with one another in order to form new embodiments.

In the following the invention will be explained in more detail with reference to the embodiment and to the drawing. There are shown:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a section of an embodiment of a rapier weaving ma-chine at the start of the weft insertion,

FIG. 2 an embodiment of a rapier head having a thread clamp in accordance with the present invention in perspective view,

FIG. 3 a detailed view of the thread clamp from the embodiment of FIG. 2,

FIGS. 3A, 3B in each case a section through the embodiment of FIG. 2 during the weft insertion and during the weft thread take-up or transfer,

FIG. 4 a detailed view of a second embodiment of a thread clamp in accordance with the present invention,

FIGS. 4A, B in each case a section through the embodiment of FIG. 4 during the weft insertion and during the weft thread take-up or transfer.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a section of an embodiment of a rapier weaving machine 20 at the start of the weft insertion. In the embodiment the rapier weaving machine includes a bringer rapier having a rapier head 10, a plurality of weft threads 2, 2′, 2″, 2′″ which are drawn off from a not illustrated thread store, warp threads 21, a colour selector 23 having a plurality of thread presenters 23 a in order to present one or more weft threads 2 to the bringer rapier for insertion and a reed 24 in order to beat up the inserted weft thread or threads at a beat-up or cloth edge. The warp threads 21 form a shed 22 between the reed 24 and the beat-up edge into which the weft thread or threads 2 are inserted. The rapier head 10 includes a thread clamp 1 in order to firmly hold the weft thread or threads 2 during the insertion. If required, the rapier weaving machine of the embodiment can have further components which are not shown in FIG. 1 such as for example a taker rapier, shed forming members, a drive and/or a control.

FIG. 2 shows an embodiment of a rapier head 10 having a thread clamp for the firm clamping of weft threads 2 in accordance with the present invention in a perspective view. The thread clamp of the embodiment includes a first and a second holding member 3, 4 which can be pressed towards one another in a clamping region 3 a, 4 a in order to hold one or more weft threads. Furthermore, one or more deflection elements 7 are provided at the thread clamp in order to deflect the weft thread or threads 2 and to increase the holding force, with at least one deflection element 7 being controllable. The first and second holding members 3, 4 and the at least one deflection element 7 can optionally be formed as lever arms which can be rotatable about an axis of rotation 5. The rapier head 10 can, if required, contain a lower part 11, an upper part 12 and in each case a side part 14 on one side or on both sides. Having regard to details relating to the construction of the thread clamp and possible variants reference is made to the following description of the detailed views in FIGS. 3, 3A, 3B, 4, 4A, 4B.

FIG. 3 shows a detailed view of the thread clamp from the embodiment of FIG. 2 and FIGS. 3A and 3B each show a section through the embodiment of FIG. 2 during the weft insertion and during the weft thread take-up or transfer. The thread clamp 1 of the embodiment includes a first and a second holding member 3, 4 which can be pressed towards one another in a clamping region 3 a, 4 a in order to hold one or more weft threads 2. Furthermore, one or more deflection elements 7 are provided at the thread clamp in order to deflect the weft thread or threads 2 and to increase the holding force, with at least one deflection element 7 being controllable.

For the actuation the at least one deflection element 7 can, if required, be provided with its own actuator in order to actuate the deflection element, in particular actuate it separately from the two holding members 3, 4, with the actuator of the at least one deflection element for example being able to be constructed as a magnetic of piezo-electric actuator. However, other suitable actuators can also be used, with the magnetic actuator having the advantage that a contact-free actuation of the deflection element is possible. The actuator can for example contain an electromagnet 8 which cooperates with a magnetizable part of the deflection element 7. The magnetic actuator can however also contain a magnetizable part, such as for example a ferro-magnetic part or a permanent magnet 8 which are connected to the deflection element 7 and which cooperate with a further magnetizable part which can be arranged outside of the rapier head, for example in a rapier tape guide of the rapier weaving machine. If required, the further magnetizable part, which is—if required—arranged in the rapier tape guide, can be designed as a permanent magnet or as the core or yoke of an electromagnet. Thanks to its own actuator the at least one deflection element 7 can be actuated and/or controlled when the weft thread or threads 2 are clamped in the thread clamp 1.

In an advantageous variant the at least one deflection element 7 is formed as a lever arm or arranged on a lever arm. Thus, it is for example possible to make the first and the second holding members 3, 4 and the at least one deflection element 7 in each case optionally as a lever arm, for example as shown in FIG. 3, as the lever arm of a two arm lever which can be pivotable about its axis rotation 5.

In a further advantageous variant the two holding members 3, 4 are designed as an automatically clamping device and/or as a passive clamping device. Thus, it is for example possible, in each case, to make the first and second holding members 3, 4 and the at least one deflection element 7 resilient or to journal them resiliently or to apply a spring force to them in order to press the holding members toward one another and/or to keep the deflection element in a defined position, for example in a position in which the weft thread or threads can be deflected or in which the deflection element frees the path of the thread. The second holding member 4 is for example as shown in FIG. 3 typically acted on by the pressure of a spring 6.1 in order to press the holding members towards one another and/or the deflection element is for example acted on by the pressure or tension of a spring 6.2. It is, however, also possible, if required, to control the contact pressure of the two holding members 3, 4 in that an additional actuator is provided for this in order to open and/or to close and/or to relief and/or to load the clamping region 3 a, 4 a of the two holding members.

In a further advantageous variant the at least one deflection element 7 is, as is shown in FIGS. 3, 3A and 3B arranged at the side of the clamping region 3 a, 4 a. Naturally it is also possible to provide a plurality of controllable deflection elements which for example can be arranged on both sides of the clamping region or optionally in the clamping region and at the side at one side or on both sides of the clamping region.

In the thread clamp 1 or in the associated rapier head one or more non-controllable or fixed deflection elements 12 a can additionally be provided in order to deflect the weft thread or threads and optionally to increase the holding force. For example a fixed deflection element 12 a can be formed at the upper part of the associated rapier head which additionally deflects the path of the thread.

FIG. 4 shows a detailed view of a second embodiment of a thread clamp in accordance with the present invention and the FIGS. 4A and 4B respectively show a section through the embodiment of FIG. 4 during the weft insertion and during the weft thread take-up or transfer. The thread clamp 1 of the second embodiment includes a first and second holding member 3, 4 which are pressed towards one another in a clamping region 3 a, 4 a in order to hold one or more weft threads 2. Furthermore, one or more deflection elements 7′ are provided at the thread clamp in order to deflect the weft thread or threads 2 and to increase the holding force, with at least one deflection element 7′ being controllable.

The second embodiment which is shown in FIGS. 4, 4A and 4B is distinguished from that shown in FIGS. 3, 3A and 3B only through the arrangement and design of the at least one controlled deflection element 7′. With regard to details for the construction of the thread clamp and possible variants reference is made to the above description of the first embodiment which was explained in conjunction with the description of FIGS. 3, 3A and 3B.

The deflection element 7′ is arranged in the second embodiment in the clamping region 3 a, 4 a of the holding members 3, 4, for example centrally in the clamping region with respect to the path of the thread. If required, a passage or cut-out can be provided in the respective holding member in the clamping region into which the at least one deflection element 7′ can be dipped in order to deflect the weft thread or threads. Naturally it is also possible to provide a plurality of controllable deflection elements which, for example, can be arranged on both sides of the clamping region and optionally in the clamping region and at the side on one side or on both sides of the clamping region.

If required, the deflection element 7′ can be made largely symmetrical and at least partly symmetrical in the longitudinal direction. For this purpose, the deflection element can for example be designed as a two-armed lever which can for example be of frame-like shape in a middle part so that the deflection element can be mounted on both sides of the first and/or second holding members 3, 4. The symmetrical or at least partly symmetrical design of the deflection element 7′ is particularly advantageous when it, as shown in FIGS. 4, 4A and 4B, is arranged approximately at the centre with respect to the clamping region 3 a, 4 a of the holding members.

An embodiment of the method in accordance with the invention will be described in the following with reference to the FIGS. 2, 3, 3A, 3B, 4, 4A and 4B. In the method for the operation of a thread clamp 1 for a rapier head 10 for a rapier weaving machine having first a second holding members 3, 4, the two holding members are pressed towards one another in a clamping region 3 a, 4 a, one or more weft threads 2 are held in the clamping region and one or more deflection elements 7, 7′, 12 a are provided by means of which the weft thread or threads 2 can be deflected and the holding force of the thread clamp can be increased. In addition, for the insertion of the weft thread or threads 2 respectively at least one deflection element 7, 7′ is controlled. If required, the at least one controlled deflection element 7, 7′ can be controlled for each individual weft insertion

In an advantageous embodiment of the method, during the take-up and/or transfer of the weft thread or threads 2 the at least one controlled deflection element 7, 7′ is, as shown in FIGS. 3B and 4B, withdrawn and/or the weft thread or threads is/are additionally held during the insertion through the at least one controlled deflection element in that the latter, as shown in FIGS. 3A and 4A dips into the path of the thread.

In a further advantageous embodiment of the method the at least one controlled deflection element 7, 7′ is withdrawn from the path of the thread for the transfer of the weft thread or threads 2 to the taker rapier and finally the weft thread or threads are drawn out of the clamping region 3 a, 4 a arranged in the bringer rapier head.

In a further advantageous embodiment of the method the weft thread or threads 2 are drawn for take-up into the clamping region 3 a, 4 a, are held by the holding members 3, 4 which are pressed towards each other in the clamping region and finally the at least one controlled deflection element 7, 7′ is dipped into the path of the thread.

Furthermore, the invention includes a rapier weaving machine having a thread clamp 1 in accordance with one of the above-described variants and/or with a rapier head 10 in accordance with the above description and/or equipped for carrying out a method in accordance with the above description.

The thread clamp, the rapier head and the method in accordance with the above-description have the advantage, in comparison to thread clamps from the prior art, that the same thread clamp can be used for a comparatively broad selection of different weft threads such as for example weft threads with different fineness, different texture or of different materials. The same applies in particular also to the case in which a plurality of different weft threads are to be inserted one after the other or simultaneously. If the holding members are formed as a passive clamping device then, thanks to the controlled deflection element, a higher holding force can be achieved, with the power and energy consumption for the actuation of the deflection element being smaller than the power and energy consumption for the actuation of a customary controlled thread clamp. 

1. Thread clamp for a rapier head (10) for the firm clamping of weft threads (2, 2′, 2″, 2′″) in a rapier weaving machine, said thread clamp (1) having first and second holding members (3, 4) which can be pressed against one another in a clamping region (3 a, 4 a) in order to hold one or more weft threads, and in which one or more deflection elements (7, 7′) are provided at said thread clamp in order to deflect the weft thread or threads (2, 2′, 2″, 2′″) and to increase the holding force, characterized in that at least one deflection element (7, 7′) is controllable.
 2. Thread clamp in accordance with claim 1, wherein the at least one deflection element (7, 7′) has its own actuator (8) in particular a magnetic actuator, in order to actuate the deflection element, in particular actuate it separately from the two holding members (3, 4).
 3. Thread clamp in accordance with claim 1, wherein the at least one deflection element (7, 7′) can be controlled, when the weft thread or threads (2, 2′, 2″, 2′″) are clamped in the thread clamp.
 4. Thread clamp in accordance with claim 1, wherein the two holding members (3, 4) are made to clamp automatically and/or as a passive clamping device.
 5. Thread clamp in accordance with claim 1, wherein the at least one deflection element (7, 7′) is formed as a lever arm or is arranged on a lever arm.
 6. Thread clamp in accordance with one of the claim 1, wherein the at least one deflection element (7, 7′) is arranged in the clamping region (3 a, 4 a).
 7. Thread clamp in accordance with one of the claim 1, wherein the at least one deflection element (7, 7′) is arranged to the side of the clamping region (3 a, 4 a).
 8. Rapier head with a thread clamp (1) in accordance with claim
 1. 9. Method for the operation of a thread clamp (1) for a rapier head (10) of a rapier weaving machine having first and second holding members (3, 4), in which method the two holding members are pressed towards one another in a clamping region (3 a, 4 a), one or more weft threads (2, 2′, 2″, 2′″) are held in the clamping region and one or more deflection elements (7, 7′, 12 a) are provided by means of which the weft thread or threads are deflected and the holding force of the thread clamp is increased, characterized in that at least one deflection element (7, 7′) is controlled for the insertion of the weft thread or threads respectively.
 10. Method in accordance with claim 9, wherein the at least one controlled deflection element (7, 7′) is controlled for each individual weft insertion.
 11. Method in accordance with claim 9 or claim 10, wherein, during the take-up and/or the transfer of the weft thread or threads (2, 2′, 2″, 2′″) the at least one controlled deflection element (7, 7′) is withdrawn and/or wherein the weft thread or threads is or are additionally held by the at least one controlled deflection element during the insertion in that it is dipped into the path of the thread.
 12. Method in accordance with one of the claim 9, wherein the weft thread or threads (2, 2′, 2″, 2′″) is/are drawn for the reception into the clamping region (3 a, 4 a), is/are held in the clamping region by the holding members (3, 4) which are pressed towards each other and wherein at least one controlled deflection element (7, 7′) is subsequently moved into the path of the thread.
 13. Method in accordance with one of the claim 9, wherein, for the transfer of the weft thread or threads (2, 2′, 2″, 2′″) to the taker rapier, the at least one controlled deflection element (7, 7′) is withdrawn from the path of the thread and following this the weft thread or threads (2, 2′, 2″, 2′″) is/are withdrawn from the clamping region (3 a, 4 a).
 14. Rapier weaving machine having a thread clamp (1) in accordance with claim
 1. 15. Rapier weaving machine having a rapier head (10) in accordance with claim
 8. 16. Rapier weaving machine equipped to carry out a method in accordance with claim
 9. 